In recent years, systems using vehicle-mounted cameras (e.g., Blind Corner Monitor: BCM) have been introduced for the purpose of preventing collision accidents, etc., upon entry into out-of-sight intersections, T junctions, etc.
In BCM, for example, a blind spot area not directly observable to a driver from the driver seat is captured by a camera installed in the front end or the like of the vehicle and the area is displayed on a vehicle-mounted monitor. With BCM, it is possible to visually assist the driver.
However, when a vehicle enters a road at an angle other than 90°, such as entering an intersection where the intersecting roads are not perpendicular to each other, road conditions on the left and right sides of the vehicle may not be simultaneously displayed on the BCM vehicle-mounted monitor. That is, there may arise blind spots that do not appear even on the BCM monitor. Further, in some cases, utility poles, pedestrians, etc., may become shielding objects, whereby the driver may not be able to grasp the left and right conditions even by looking at the image on the BCM monitor. In such a case, the driver may not be aware of an approaching vehicle, meaning that road safety may not be confirmed to a sufficient degree with BCM alone.
Meanwhile, as a means for preventing accidents, mirrors (corner mirrors) that reflect information on areas that are blind spots for drivers are placed at intersections.
An obstacle detection system using such mirrors installed on roadsides has been proposed (see Japanese Laid-open Patent Publication No. 2007-69777 (Patent document 1), for example). In this system, infrared light is irradiated from a vehicle to a reflector installed on a roadside and the presence or absence of a dangerous object is determined based on an image produced from the infrared light reflected on the reflector. When a dangerous object is present, the system notifies the driver as such.
Further, there has also been proposed a system in which a corner mirror is identified from an image captured by a camera installed in the front end of a vehicle and a magnified image of the corner mirror is displayed on a HUD (Head-Up Display) (see Japanese Laid-open Patent Publication No. 2007-102691 (Patent document 2), for example).    Patent document 1: Japanese Laid-open Patent Publication No. 2007-69777    Patent document 2: Japanese Laid-open Patent Publication No. 2007-102691
However, depending on conditions such as the size, shape and direction of each corner mirror and road width, areas (blind spots) that may not be captured even by corner mirrors may arise. For this reason, drivers may not be able to confirm road safety to a sufficient degree with corner mirrors and their magnified image alone.
As described above, since the situation in blind spot areas changes momentarily, it is necessary for drivers to check at all times both the BCM image and corner mirrors installed on roads or an image thereof. For example, immediately before entering an intersection, the driver may make movements such as taking a look at mirrors placed on the road to check information on blind spot areas captured by the mirrors and taking a look at the monitor to check information on blind spot areas captured by a BCM camera. Such actions are a burden on drivers driving vehicles.
That is, even if the environment for presenting blind spot areas and a magnified image to drivers through BCM and corner mirrors is put into place, when the drivers cannot check information on the blind spots and on the magnified image through a single action (action such as checking the monitor), the benefits of the information are halved.
For this reason, a mechanism that allows drivers to perceive the information on both the blind spot areas and the magnified image through a single action and to make full use of the both information is desired.